1. FIELD OF THE INVENTION
The present invention relates to pin grid arrays and more particularly to a tool designed to facilitate the removal of elements such as pin grid arrays which are either surface mounted or soldered into plated through holes in printed wiring cards.
2. BACKGROUND INFORMATION
Pin grid arrays are being designed into products to take advantage of their high packaging density, versatility and high speed operation. Pin grid arrays are available in ceramic packages which are either surface mounted or soldered into plated through holes in a printed wiring card. In many applications, pin grid arrays are inserted into sockets which are in turn soldered into plated through holes in printed wiring cards. In many instances these devices are attached to multilayer printed wiring boards that are very expensive to manufacture. In the ordinary course of events it frequently becomes necessary for a pin grid array or similar device to be removed and replaced with another such device either as a repair procedure or as a result of a design modification. Both of these procedures require that the original device be removed without damaging the very expensive printed wiring card which in turn may have many other expensive components already attached to it.
Pin grid arrays and chip carriers and pin grid array sockets and chip carrier sockets are usually soldered to printed wiring cards by means of wave soldering techniques or solder reflow techniques. Wave soldering is used when through-hole mounted devices are used. On the other hand, solder reflow methods such as vapor phase soldering or infrared soldering are used when surface mounted devices are specified. The majority of pin grid arrays are soldered into the plated through holes in the printed wiring card to facilitate solder joint inspection from the back side of the printed wiring card. The use of surface mounted pin grid arrays covers the surface attaching soldering joints and thus prevents visual inspection after soldering.
It has been determined that pin grid arrays frequently become the device of choice over chip carriers when the input/output lead count exceeds 100. Applying enough heat to simultaneously unsolder 100 or more solder joints without causing damage to the printed wiring card is the principal requirement that needs to be accomplished. It has been determined by experience that the soldering process used to attach the component is probably the best and safest process used to remove the component. However, one does not reach into a vapor phase soldering machine, an infrared machine or a wave soldering machine and lift the pin grid array off the printed wiring card while the solder is still in a molten state. Obviously the temperatures in such an environment are far in excess of that which can be handled manually.
Accordingly, a need is clearly established for some kind of self-actuated removal tool that is able to withstand the high temperatures of the vapor phase, infrared or wave soldering environments, in order to accomplish this final step of a pin grid array removal process. The very same function of lifting the device while the solder is molten is required to replace pin grid array sockets, chip carriers and chip carrier sockets. Accordingly, it is the object of the present disclosure to develop a removal tool which will greatly simplify the repair and replacement procedure of removal of the pin grid array or similar element from the printed wiring cards.